New Evaluation Method for Cross-Contamination of Ion Implantation by Using Grazing Angle Incidence PIXE in Photo-Resist

Two orders of magnitude improvement have been accomplished in detection limit of areal density of impurity atoms introduced into semiconductor devices during ion implantation, for the evaluation of the crossing contamination.Impurity atom concentrations as low as 1 × 10¹² cm^-2 can be successfully detected using these new methods. The first point is the use of grazing incidence of 87^° of the probe beam for particle induced X-ray emission (PIXE) analysis, which lowers the detection limit to 1 × 10¹³ cm^-2 for arsenic contaminants. The second point is the use of photo-resist covered Si wafers, which allows detection of As cross contamination at normal PIXE beam incidence to the order of 1 × 10¹³ cm^-2 through the reduction of Si bremsstrahlung background in the X-ray spectra. The combination of both procedures lowers the detected As level to 1 × 10¹² cm^-2.